I have to admit to mixing the wormer in grain for one horse I have. He is a good enough horse, huge and quite broke, but if he sees wormer you'd better watch out. My husband was convinced I was simply being a girl and quickly learned he couldn't 'show me how to do it.' The horse will come at you and try to strike you if you push it.
So, I don't. We've never had to medicate him but for one colick and we have him a shot of banamine in that instance. He is so funny, he loves food so he eats the grain, but when he tastes the wormer he gets mad and starts running his teeth in the gravel. It's always quite the show. Lol. Then his guy gets the best of him and he finishes up the grain.